1. Field of the Invention
The present invention relates to a method of manufacturing calcium phosphates in which compositions containing phosphorus such as particularly phytin in the plants are used as a supply source of phosphorus, more particularly to such a method of providing a market with a product that is fully superior in quality and remarkably lower in price as compared with that of the prior art.
2. Description of the Prior Art
(a) As a manufacturing method of calcium phosphates well known hitherto, there is a method which firstly starts from inorganic materials, for example, inorganic rock phosphate such as inorganic materials such as apatite, ash phosphate, guano ore and the like. Phosphoric acid is manufactured from these materials. Then lime is added to the phosphoric acid to synthesize calcium phosphate. The disadvantage of this method will be discussed later.
(b) As another method of the prior art, there is a method which treats the bones of animals with acid and hot water to remove gelatin thereby obtaining phosphoric acid lime especially such as the mixture of natural hydroxylapatite Ca.sub.10 (PO.sub.4).sub.6.(OH).sub.2 and orthophosphoric acid. Further,there is a method of obtaining synthetic calcium phosphate by chemically collecting phosphorus component that is lost in the process of removing gelatin. The disadvantages of these methods will also be discussed later.
(c) As a relatively new prior art, there is a manufacturing method as disclosed in the Patent Public Disclosure No. 223,209/1984 Official Gazette (entitled "Manufacturing method of calcium phosphate for the porcelain and the porcelain of calcium phosphate system"). The gist of this manufacturing method described in the claim of the specification of the publication is as follows: In this method,carbonate of alkaline earth method is added to phytin which is separated from the rice bran. The carbonate may not be added. Then hydrolysis is executed at the temperature over 100.degree. C. under pressure. Thereafter, pH is regulated in the range between 5 and 8. Then the resultants is filtrated to obtain calcium phosphate. As discussed hereinbefore,this method can be divided roughly into two categories, that is, one category in which carbonate of alkaline earth metal is added and the other category in which carbonate is not added. Furthermore, since the contents of this method varies extremely according to the fact that carbonate of alkaline earth metal is Ca salt or Mg salt. Thus this method is still discriminated into two categories and therefore it is divided into three categories. The disadvantages of this method will be discussed hereinafter.
Now the disadvantages of the aforementioned manufacturing methods are discussed. In the prior art (a), natural rock phosphates are used as raw material and are limited resources which are going to be exhausted year by year in the whole world. Accordingly there is a tendency to raise their cost on the whole. Thus such resources will not be expected too much as raw material in the near future. Particularly, there has been arisen such a serious problem that the supply of such raw material is unstable in many countries since it is almost dependent upon the import.
Furthermore,since fluorine, uranium and rare earth elements are contained in apatite,the difficult operations are required to remove them. Accordingly the manufacturing cost become extremely expensive. The increasing rise of price of calcium phosphates is inevitable by reason of exhaustion of the resources. In this regard,it is as high in cost as 270,000 or higher per ton even at present.
Since the calcium phosphates are synthetic products and therefore their quality are very solid, it is considerably difficult to treat them for use. Accordingly there is a such problem that the range of its use as the material for organism and the like are limited due to their quality.
As to the prior art (b), natural bones of animals are used as the raw material and therefore their supply amount are restricted due to the natural product. Thus the price thereof become extremely high as almost 300,000 or higher per ton. As a result,there is a such problem that it is difficult to use it as general industrial materials.
Furthermore,since the qualities of the bones of the animals differ from each other according to the breeding and life of each animal,there is a such problem that it is difficult to obtain calcium phosphate with uniform quality.
Moreover,the method of manufacturing synthetic calcium phosphate by collecting the phosphorus components which depart from in the gelatin removing process has a such problem that the melting point of the calcium phosphate become lower and therefore its uses are limited within a narrow range.
Additionally,it has such a disadvantage that odor generation is enormous in the process of obtaining calcium phosphate from the resource of the animals, thereby causing air pollution.
Concerning the prior art (c), according to the claims of the specification of the Patent Public Disclosure No.223,209/1984 Official Gazette, such method as to add calcium carbonate among carbonates of alkaline earth metal to phytin separated from the rice bran is carried out as follows: the hydrolysis is made at a temperature over 100.degree. C . Then pH of the liquid is regulated in the range between 5 and 8 to cause the precipitations of calcium hydrogenphosphate. They are filtered to provide as the filtrate the inositol solution for another use (raw materials for the seasonings etc.) and to provide as the precipitation calcium phosphate. However, since calcium phosphate is produced in the acid solution according to the embodiments, calcium phosphate has, for example, Mg derived from the rice bran at pH of 5.8 and tends to become Ca.sub.7 Mg.sub.2 (PO.sub.4).sub.6. Further,a large quantity of H+ radicals exist in the composition. Thus the basis containing much H+radicals is unstable in component and accordingly the melting point of the calcium phosphate goes down. Thus it does not enough in strength and thermal resistance even after it is purified and kneaded to be shaped and baked. There is such a problem that it does not have sufficient quality as the raw material for the porcelain. Further,there are such problems that it is not adequate for the porcelain material such as so-called bone china and the like as it is since calcium phosphate formed in the acid solution contains a lot of brushite CaHPO.sub.4.2H.sub.2 O and monetite CaHPO.sub.4. Additionally,it may not be used as the material of the organism of the recent new ceramics since the property of it is totally different from that of hydroxylapatite Ca.sub.10 (PO.sub.4).sub.6 (OH).sub.2.
Besides,in this prior art (c) the plants are used as the raw material so that calcium phosphate contains a lot of carbohydrate. However, there is no operation to remove carbons in this manufacturing method and therefore has the following defects: If the porcelain is burned in an ordinary manner using calcium phosphate produced by this method, carbons are fixed and liberated so that the product of the porcelain become black and cannot be colored freely.
Then, in case of adding magnesium carbonate, talc and the like among carbonates of the alkaline earth metals to phytin separated from the rice bran,there is such a disadvantage that the use of the glazes is limited because Mg is further added to the natural Ca.sub.7 Mg.sub.2 (PO.sub.4).sub.6 to lower the melting point of the product.
Furthermore,in the method of adding no carbonate of the alkaline earth metal in the prior art (c), since there are little Ca source or Mg source, phosphoric acid is formed; however calcium phosphate and magnesium phosphate are not formed at all even by pressure superheating in the autoclave. Otherwise a very small amount of them may be formed. As a result, inositol is mainly formed by this method. Accordingly, this prior art is also highly unsatisfactory as the method of manufacturing calcium phosphate.
As discussed hereinbefore, this prior art (c) may be excellent as compared with the other prior arts from the viewpoint of finding the rice bran as the resource of phosphoric acid. However it can not contribute to actually produce calcium phosphate used for the raw material for the porcelain and the material used in the organism in the respect of the contents of the concrete technique. It will be understood that this seems to be an unfinished invention and therefore it is clear that even if such conception is obtained by those technical experts and researchers it could not be easily realized to them to complete the embodied method of manufacturing excellent calcium phosphate in practice.